COAGULATION OF THE BLOOD. 
649 
vital properties, and comport themselves like ordinary solids. 
Thus, when an artery or vein is inflamed, coagulation occurs 
upon its interior, in spite of the current of blood, precisely 
as would take place if it had been artificially deprived of its 
vital properties. On one occasion I simulated the charac¬ 
teristic adherent clot of phlebitis b} 7 treating the jugular vein 
of a living sheep with caustic ammonia, and then allowing 
the circulation to go on through the vessel for a while, when, 
on slitting it up, 1 found its lining membrane studded with 
grains of pink fibrin, which could be detached only by 
scraping firmly with the edge of a knife. Again, comparing 
ar inflammatory exudation into the pericardium or into the 
interstices of the cellular tissue with dropsical effusions into 
the same situations, we are struck with the fact that, while 
the liquor sanguinis effused in dropsy remains fluid, the 
inflammatory product coagulates. Now we know that ill 
intense inflammation the capillaries are choked, more or less, 
with accumulated blood-corpuscles, which must cause great 
increase in the pressure of the blood upon their walls; and 
from what we know of the effect of venous obstruction in 
causing dropsical effusion of liquor sanguinis through in¬ 
creased pressure, we are sure that we have in the inflamma¬ 
tory state the physical conditions for a similar transudation 
of fluid through the walls of the capillaries. And the natural 
interpretation of the difference in the two cases as regards 
coagulation seems to be, that whereas in dropsy the fluid is 
forced through the pores of healthy vessels, in inflammation 
the capillary parietes have lost their healthy condition, and 
act like ordinary matter; so that the liquor sanguinis, having 
been subjected, immediately before effusion, to the combined 
influence of the injured tissue and the blood-corpuscles, has 
acquired a'disposition to coagulate, just like the buffy coat of 
horses’ blood shed into a glass, or like the frog’s liquor san¬ 
guinis filtered by Muller from its corpuscles, the injured 
vessels acting upon the blood like the filter. 
This view of the condition of intensely inflamed parts is 
exactly that to which I was led some years ago by a micro¬ 
scopic investigation, the results of which were detailed in a 
paper* that received the honour of a place in the c Philo¬ 
sophical Transactions.’ It was there shown, as I think 
I may venture to say, that the tissues generally are capable 
of being reduced, under the action of irritants, to a state 
quite distinct from death, but in which they are nevertheless 
temporarily deprived of all vital power; and that inflamma- 
* “ On the Early Stages of Inflammation,” ‘ Phil. Trans./ for 1858. 
xxxvii. 42 
